Chemistry Project

Democritus

400 BCE

First to theorize that atoms were specific to material. Atoms were different in shape and size. Constant motion, and stuck to each other. Divided a seashell to theorize how small matter could be.

Antoine Lavoisier

1772

Pioneer of stoichiometry. He showed that matter could change state in a chemical reaction. The total mass remains the same. “Nothing is lost, Nothing is created, everything is transformed.”

John Dalton

1808

Theorized Atoms were indivisible and indestructible with distinct masses and properties.
Oxygen combined with one or to volumes of nitric oxide in closed vessels over water.

J.J. Thomson

Apr 30, 1897

Discovered electrons and made plum pudding model.
Used Cathode ray tubes to show all atoms contain electrons.

Marie Curie

1898

Discovered radium and podium. Radioactivity originates with the atoms themselves.
Investigated pitchblade to find elements.

Ernest Rutherford

1899

Discovered that atoms contain a nucleus much smaller than the atom.
Gold foil experiment particles shot at gold foil show most passed through some didn’t.

Max Planck

1900

Introduced the quantum theory explains the behavior of matter and energy.

Albert Einstein

1905

Used equations and math to prove the atoms' existence.
Used mostly math to experiment with atoms equations and theories to prove things happen without experimenting directly.

Robert Millikan

1910

Discovered the accurate charge of an electron.
Used falling drop method: Small electrically charged drops of oil were suspended between two metal plates where they were subjected to the downward force of gravity and the upward attraction of an electrical field.

Niels Bohr

1913

Bohr model, and discovered some physicals values only take discrete values.
Nuclear fission splitting nucleus of atom to experiment.

Louis De Broglie

1924

Waves can be used the same way as particles.
Streams of electrons reflected against crystals and spread through metal foils.

Werner Heisenberg

1925

Made a type of quantum mechanics based on matrices. Set limits for particles.
Gamma ray microscope illumination would cause the electron to move.

Erwin Schrodinger

1926

Wave equation calculates the energy of electrons.
Schrodingers cat experiment hypothesized that atoms are in decay and non decay until it is observed.

James Chadwick

1932

Discovered Neutron.
Shot alpha particles at beryllium producing what he called neutrons.